1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image on an image-forming medium carried.
2. Description of the Related Art
An ink-jet printer injects liquid ink at a paper to print an image thereon. In general, in the ink-jet printer, a long paper is fed on a carrying table disposed to confront a print-head having a number of ink injecting nozzles in sequence from its tip, with its orientation restricted by a pair of guide members disposed at both widthwise end portions of the long paper, to print an image on the paper. In general, the print-head is structured to reciprocally move along a direction perpendicular to a carrying direction of the paper, while injecting the ink at the paper, to print the image thereon.
This type of printer sometimes tries to obtain improved processing power by arranging papers in two rows to confront the print-head so that the image can be printed on those two papers nearly simultaneously. In this arrangement, the widthwise positions of the papers arranged in two rows are restricted separately by two pairs of guide members arranged in correspondence to those two papers, respectively. The two pairs of guide members are each movable along a widthwise direction of the paper (a direction perpendicular to the carrying direction of the paper) so that they can be adjusted in position in accordance with the width of the paper to be in correspondence with both widthwise ends of the paper. This means that the two pairs of guide members positioned in correspondence with the papers arranged in two rows are arranged in parallel with each other on a same plane as a carrying surface of the paper.
Also, each pair of guide members restrict the widthwise position of the paper so that the widthwise center of the paper can conform (center alignment), irrespective of width of the paper. In general, the pair of guide members are movable in a specific range only, so that the distance between the both guide members is not widened beyond a specified distance (maximum distance).
Some carrying table for supporting the papers confronting the print-head is provided with ink receiving portions for receiving the ink protruding from the paper margin when the image is printed on the paper in a rimless form. This type of carrying table is, in general, provided with a number of ink receiving portions disposed adjacent to both ends of the papers having different widths, so as to adequately print the image on the paper in the rimless form regardless of width of the paper.
In this type of printer, when the image is printed on papers arranged in two rows while the print-head is moved forward or backward along the widthwise direction of the papers, as mentioned above, the image is printed on the paper while the print-head is in a position confronting the paper, but the image is not printed on the paper while the print-head is in a position confronting a space between the papers.
If the two pairs of guide members which are movable separately in the widthwise direction of the paper with respect to the papers arranged in two rows are provided in this type of printer, the mechanism for restricting the widthwise position of the paper will be complicated. This problem of complication of the mechanism for restricting the widthwise position of the paper arises not only when the papers are fed in two rows but also when the papers are fed in single row. Also, if the distance between the papers arranged in two rows is large, then the time for the print-head moved forward or backward to be in the position confronting the space between the papers, during which the image is not printed on the paper, becomes longer and, as a result, the processing power of the printer reduces.
Also, if this type of printer is used to print an image on the paper having a larger width than a maximum distance between the pair of guide members, then the both widthwise ends of that wider paper can no longer be restricted by the pair of guide members. Although it is conceivable that the both widthwise ends of that wider paper is restricted by using two guide members of one pair located at the widthwise outside of the guide members of another pair, since the two guide members of another pair located at the widthwise inside are on the carrying surface of such a wider paper, the wider paper will not be fed precisely. Thus, this type of printer cannot feed the paper having a larger width than the maximum distance between the two guide members of the pair, while the both widthwise ends of the paper are restricted on the carrying surface of the paper. As a result, this type of printer cannot be used to print the image on the paper having such a wider width.
It is one object of the present invention to provide an image forming apparatus that can provide a simplified mechanism for restricting widthwise positions of image-forming media of different widths.
It is another object of the present invention to provide an image forming apparatus that can provide an improved processing power by shortening the time for an image-forming member be in a position confronting the space between the image-forming media during which the image is not formed on the image-forming media.
It is yet another object of the present invention to provide an image forming apparatus that can restrict a widthwise position of each of image-forming media having a relatively narrow width arranged in rows, while carrying the image-forming media, and also can restrict a widthwise position of image-forming media having a width stretching over carrying passages of the image-forming media having the relatively narrow width, while carrying the image-forming media.
In accordance with the first aspect of the present invention, there is provided an image forming apparatus comprising carrying means for carrying an image-forming medium; a first position restricting member, unmovable in a widthwise direction of the image-forming medium, for restricting a position of one widthwise end of the image-forming medium carried by the carrying means; a second position restricting member, movable in a widthwise direction of the image-forming medium, for restricting a position of the other widthwise end of the image-forming medium; and an image-forming member for forming an image on the image-forming medium carried by the carrying means, the positions of both widthwise ends of the image-forming medium being restricted by the first position restricting member and the second position restricting member.
According to this construction, the first position restricting member for restricting a position of one widthwise end of the image-forming medium is unmovable in a widthwise direction of the image-forming medium, while only a second position restricting member for restricting a position of the other widthwise end of the image-forming medium. This construction can allow simplification of the mechanism for restricting the widthwise position of the image-forming medium, as compared with the construction wherein both of the first and second position restricting members are movable in the widthwise direction of the image-forming medium so that the widthwise position of the image-forming medium can be restricted by moving both of the first and second position restricting members.
Suppose that the image forming apparatus is an ink-jet printer wherein the image-forming member injects inks at the image-forming medium to print an image thereon and the image is printed on the image-forming medium of different widths in a rimless form: According to the construction of the invention, one end of the image-forming medium restricted by the first position restricting member can be positioned conformably, irrespective of the width of the image-forming medium. This can provide a common ink receiving portion for any of the image-forming medium of different widths when the ink receiving portion is positioned near the one end of the image-forming medium. This can provide a reduced number of ink receiving portions arranged in the ink-jet printer, and as such can produce simplification of the manufacturing process.
It is preferable that the carrying means carries a plurality of image-forming media arranged in substantially parallel with each other, and wherein at least one of the two first position restricting members and the two second position restricting members, each of which are arranged in correspondence with the two image-forming media arranged adjacent to each other to make a pair, is formed in one piece.
This construction can provide a reduced number of parts for the mechanism for restricting the widthwise position of the image-forming media, and as such can provide further simplification of that mechanism and further reduction of manufacturing costs.
It is preferable that the carrying means carries a plurality of image-forming media arranged in substantially parallel with each other, wherein the image-forming member forms an image while it moves reciprocally along a direction perpendicular to the carrying direction of the image-forming media, and wherein the two first position restricting members, which are arranged in correspondence with the two image-forming media arranged adjacent to each other to make a pair, restrict the positions of the two image-forming media making a pair at their opposing widthwise ends.
According to this construction, the positions of the two image-forming media making a pair at their opposing widthwise ends are restricted by the first position restricting member unmovable in a widthwise direction of the image-forming media. This can provide the result that irrespective of the width of the image-forming media, the two image-forming media making a pair are spaced from each other at a predetermined distance, differently from the case where the widthwise positions of the two image-forming media making a pair are restricted by the center alignment and the case where the positions of the two image-forming media making pair at one widthwise end thereof on the side thereof identical with each other are restricted by the first position restricting member. This can provide the result that when the predetermined distance between the two image-forming media making the pair is set at a shortened distance, the time for the image-forming member to be in the position confronting the space between the image-forming media in the frontward and backward movement of the image-forming member during which no image is printed (the free-running distance at which the image-forming member moves between the image-forming media without printing any image) can be shortened. This can provide an improved processing power of the image forming apparatus.
It is preferable that the first position restricting member can selectively take either a position where at least a part of the first position restricting member locates on the substantially same plane as the carrying surface of the image-forming media or a position where the whole of the first position restricting member does not locate on the substantially same plane as the carrying surface of the image-forming media.
According to this construction, the first position restricting member disposed between the carrying passages of the two image-forming media making the pair is switched from a position where the whole of the first position restricting member does not locate on the substantially same plane as the carrying surface of the image-forming media. This can provide the result that widthwise positions of the image-forming medium having a width spreading across the carrying passages of the two image-forming media making the pair can be properly restricted by the second position restricting member, while the image-forming media is carried.
In accordance with the second aspect of the present invention, there is provided an image forming apparatus comprising carrying means for carrying an image-forming medium; and at least three position restricting members, each of the position restricting members restricting a position of one widthwise end of the image-forming medium, being spaced from one another along a widthwise direction of the image-forming medium, wherein at least one of the at least three position restricting members, except the two position restricting members arranged at outermost positions, can selectively take either a position where at least a part of the position restricting member locates on the substantially same plane as the carrying surface of the image-forming medium or a position where the whole of the position restricting member does not locate on the substantially same plane as the carrying surface of the image-forming medium.
According to this construction, the position restricting member arranged between the position restricting members disposed to be in correspondence with the both widthwise ends of the image-forming media is switched from the position where the whole of the position restricting member does not locate on the substantially same plane as the carrying surface of the image-forming medium. This can provide the result that the positions of both widthwise ends of the image-forming medium having different widths can be properly restricted by the position restricting members, while the image-forming medium is carried.
When a plurality of position restricting members are arranged on the substantially same plane as the carrying surface of the image-forming medium and are spaced from one another along the widthwise direction of the image-forming medium, both widthwise ends of the image-forming medium having different widths can be properly restricted, while the image-forming medium is carried. In a specific range in which the position restricting members are arranged, the image-forming medium having a relatively narrow width can be carried in the condition of being arranged in rows and the image-forming medium having a relatively larger width can be carried in the condition of being carried in a single row.
It is preferable that at least one of the position restricting members is movable in a widthwise direction of the image-forming medium.
According to this construction, since the positions of the position restricting members can be adjusted in accordance with the width of the image-forming medium, the positions of both widthwise ends of the image-forming medium having different widths can be restricted further properly, while the image-forming medium is carried.
It is preferable that at least one of the position restricting members restricts the positions of two image-forcing media arranged adjacent to each other to make a pair at their opposing widthwise ends.
According to this construction, one position restricting member serves as a common member for restricting the widthwise position of the two adjacent image-forming media. This can provide a reduced number of parts of the mechanism for restricting the widthwise positions of the image-forming media, and as such can provide a further simplified mechanism and a reduced manufacturing cost.
It is preferable that there is further provided switching means switches each positions of the position restricting members.
According to this construction, since the position of the position restricting member can be switched by the switching means, the position switching operation of the position restricting member in accordance with various image-forming medium of different widths can be accelerated and facilitated.
It is preferable that the position restricting member switched into the position where the whole of the position restricting member does not locate on the substantially same plane as the carrying surface of the image-forming medium by the switching means is able to abut with an image-forming side or an opposite side of the image-forming medium carried by the carrying means.
According to this construction, the both widthwise ends of the image-forming medium are restricted by the position restricting members arranged to be in correspondence with both widthwise ends of the image-forming media. In addition, the position restricting member switched into the position where the whole of the position restricting member does not locate on the substantially same plane as the carrying surface of the image-forming medium by the switching means be able to abut with the image forming side of the image-forming medium or the opposite side of the same. Therefore, the positions of both widthwise ends of various image-forming medium of different width can be restricted further precisely on the carrying surface of the image-forming medium.